This invention relates to a protocol for providing parallel, multi-threaded processors with high bandwidth access to shared resources.
Parallel processing is an efficient form of computer information processing of concurrent events. Certain problems may be solved by applying parallel computer processing, which demands concurrent execution of many programs to do more than one thing at the same time. Unlike a serial paradigm where all tasks are performed sequentially at a single station, or a pipelined machine where tasks are performed at specialized stations, parallel processing requires that a plurality of stations have the capability to perform all tasks. In general, all or a plurality of the stations work simultaneously and independently on the same or common elements of a problem.
Types of computer processing include single instruction stream, single data stream, which is the conventional serial von Neumann computer that includes a single stream of instructions. A second processing type is the single instruction stream, multiple data streams process (SIMD). This processing scheme may include multiple arithmetic-logic processors and a single control processor. Each of the arithmetic-logic processors performs operations on the data in lock step and are synchronized by the control processor. A third type is multiple instruction streams, single data stream (MISD) processing which involves processing the same data stream flows through a linear array of processors executing different instruction streams. A fourth processing type is multiple instruction streams, multiple data streams (MIMD) processing which uses multiple processors, each executing its own instruction stream to process a data stream fed to each of the processors. MIMD processors may have several instruction processing units and therefore several data streams.
According to an aspect of the present invention, a parallel, hardware-based, multi-threaded processor includes a global command arbiter for determining the allocation of access to system resources. The multi-threaded processor system includes a plurality of microengines, a plurality of shared system resources and a global command arbiter. The global command arbiter uses a command request protocol based on the shared system resources and command type to grant or deny a microengine command request for a shared resource. The processor system may be advantageously realized on an integrated circuit chip with minimal wiring and buffer storage elements.
The technique according to the invention provides each microengine with fair access to the shared system resources based on command priority and resource utilization. Consequently, the microengines have high bandwidth access to the shared system resources.